The co-founder and CEO of Siri, responsible for developing the voice recognition technology in the iPhone 4S, has departed Apple on "amicable" terms.

Dag Kittlaus left his position at Apple after the launch of the iPhone 4S, according to Kara Swisher of All Things D. He served as CEO of Siri since 2007, and after the company was acquired by Apple in April of 2010, he led its speech recognition development.

"There were several reasons for the departure, which was amicable and has been planned for a while, sources said," Swisher wrote. "They included Kittlaus' family being in Chicago, a desire to take time off and an interest in brainstorming new entrepreneurial ideas."

His LinkedIn profile still lists his current title as director of Siri and speech recognition for iOS at Apple in the San Francisco Bay area. The other titles he currently holds are a member of the Cabrini Green Tutoring Program Board of Directors, and a founding advisor at Palindrome Advisors. He was previously an entrepreneur-in-residence at Stanford Research Institute, and a general manager at Motorola.

Siri technology is one of the main selling points of the iPhone 4S, Apple's latest smartphone model that launched earlier this month. Using natural language, users can have their phone do complex tasks like send a text message or e-mail, make or modify a calendar appointment, set reminders or alarms, or even look up information like the date of the next full moon.

Swisher said that Kittlaus departed Apple just after the launch of the iPhone 4S. Sources told her that other key executives from Siri are expected to remain with the iPhone maker.

After the iPhone 4S and its Siri voice control were unveiled on Oct. 4, Kittlaus was finally capable of speaking publicly about his work on Siri at Apple. He immediately took to Twitter that same day.

"If you are a start-up you want to get acquired by Apple," he wrote. "Fun times."

Though the Siri brand remains with the voice recognition technology found in the iPhone 4S, it is believed that Apple's implementation also uses intellectual property licensed from Nuance Communications, makers of Dragon NaturallySpeaking. Neither Apple nor Nuance have confirmed that Nuance's technology plays a part in Siri on the iPhone 4S.

I think apple will not have any problems scaling the service or adding new features without the cofounder. It's good that he stayed this long and brought his companies acquisition to a logical end, now he can go on and focus on other ideas he's got.

I would assume part of the terms of the buyout was that he would stay working for Apple for a certain period of time to help integrate that technology. Now he's done that, you can't blame the guy for wanting to spend some time with his money.

Why don't you elaborate why you think he would be embarrassed and ashamed? Your implication is that Siri is something he should be embarrassed about... so why don't you spend some time arguing that point and explaining what about the product is so embarrassing.

Why don't you elaborate why you think he would be embarrassed and ashamed? Your implication is that Siri is something he should be embarrassed about... so why don't you spend some time arguing that point and explaining what about the product is so embarrassing.

Maybe he's embarrassed and ashamed because he's doing charity work too? Or because he hasn't run his ideas past Archipellago to get the approval of a true industry visionary?

If he is involved with Cabrini Green, then he is motivated by more than money... much more.

I vividly remember making a wrong turn one night and ending up on a street near it and just wanting to get out of there ASAP. Misty night, junker cars with steamed up windows, and nothing looking all too friendly around, and certainly a wonderful rep to go with it.

He may have all the money he can use now but that's definitely not a for-profit item there, more because he wants to make a difference.

"An Apple spokeswoman declined to comment on why the company gave Siri a female voice in the U.S. Nor would she say why Siri speaks like a man in the UK, where iPhone 4S owners have swarmed online forums to request a female voice instead. "

...are the folks that expect someone like Dag to remain in a corporate culture while their personalities are entrepreneurial. Of course once Apple had embedded the new technology into the processes and development of the hardware and software, Dag would want to move on. As the article stated, he was now free to move on and develop something else new and fun, not to mention spend time with his family. Exactly the way things should work!

Entrepreneurs love the adventure of discovering, inventing and innovating. Not so much the corporate environment, even one as innovative as Apple. Go forth Dag and do something else cool again!

If you are going to insist on being an ass, at least demonstrate the intelligence to be a smart one